@@ -3251,6 +3251,9 @@ static int img_rebase(int argc, char **argv)
}
if (out_baseimg[0]) {
+ const char *overlay_filename;
+ char *out_real_path;
+
options = qdict_new();
if (out_basefmt) {
qdict_put_str(options, "driver", out_basefmt);
@@ -3259,8 +3262,26 @@ static int img_rebase(int argc, char **argv)
qdict_put_bool(options, BDRV_OPT_FORCE_SHARE, true);
}
- blk_new_backing = blk_new_open(out_baseimg, NULL,
+ overlay_filename = bs->exact_filename[0] ? bs->exact_filename
+ : bs->filename;
+ out_real_path = g_malloc(PATH_MAX);
+
+ bdrv_get_full_backing_filename_from_filename(overlay_filename,
+ out_baseimg,
+ out_real_path,
+ PATH_MAX,
+ &local_err);
+ if (local_err) {
+ error_reportf_err(local_err,
+ "Could not resolve backing filename: ");
+ ret = -1;
+ g_free(out_real_path);
+ goto out;
+ }
+
+ blk_new_backing = blk_new_open(out_real_path, NULL,
options, src_flags, &local_err);
+ g_free(out_real_path);
if (!blk_new_backing) {
error_reportf_err(local_err,
"Could not open new backing file '%s': ",
Currently, rebase interprets a relative path for the new backing image as follows: (1) Open the new backing image with the given relative path (thus relative to qemu-img's working directory). (2) Write it directly into the overlay's backing path field (thus relative to the overlay). If the overlay is not in qemu-img's working directory, both will be different interpretations, which may either lead to an error somewhere (either rebase fails because it cannot open the new backing image, or your overlay becomes unusable because its backing path does not point to a file), or, even worse, it may result in your rebase being performed for a different backing file than what your overlay will point to after the rebase. Fix this by interpreting the target backing path as relative to the overlay, like qemu-img does everywhere else. Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1569835 Cc: qemu-stable@nongnu.org Signed-off-by: Max Reitz <mreitz@redhat.com> Message-id: 20180509182002.8044-2-mreitz@redhat.com Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Max Reitz <mreitz@redhat.com> --- qemu-img.c | 23 ++++++++++++++++++++++- 1 file changed, 22 insertions(+), 1 deletion(-)